It is desirable to weigh containers during filling and closure processing to determine that the correct amount of material has been placed in the container. The apparatus disclosed in Schaltegger U.S. Pat. No. 4,848,479 for checking the weight of filled containers is referred to as a "straight-line" checkweigher because it removes the container from a supply line and then deposits it on a delivery line which is parallel to the supply line. This is desirable for space conservation.
The checkweigher disclosed in Schaltegger has an excellent container transfer mechanism, a birfurcated robotic transfer guide for clasping and releasing the containers, but the epicycloidal motion of that guide, from pick-up to delivery, derives from the fact that it is driven by a planetary gear traveling around the (Pg. 10) periphery of its drive gear, a complex, expensive and space consuming mechanism.
Each transfer guide of the apparatus disclosed in Schaltegger provides a pair of concave container receiving and transferring elements of approximately equal arcuate extension; one stabilized relative to a shaft extending from a planetary gear and one pivoted relative to the shaft to close about and open to release the processed container. Such a construction eliminates the need for guide rails, but requires additional peripheral operating room to accommodate the epicycloidal movement of the transfer guides and the planetary action of their gear actuators.
Furthermore, because of the space requirements for the gearing and planetary travel of the guides, the weigh station must be located out of the operative field of the gear mechanisms, thus resulting in machinery having relatively large floor dimensions. This is never totally acceptable to container processors for reasons of economy, as well as the desire to have the containers processed quickly through as small a processing area as possible.
Checkweighing apparatus and other container processing apparatus weigh stations are necessarily adjacent or surrounded by very fast moving drive and guide mechanisms which cause vibration within the apparatus and inaccuracy in the weighing readout. Close tolerance machining and counter moving drives may minimize vibration but at excessive costs and not sufficiently to guarantee weighing accuracy within desirable parameters.
The objects of the present invention include the provision of container processing apparatus with simplified driving and guiding trains facilitating very fast processing, particularly weighing, of containers with high accuracy and the provision of such apparatus using minimal floor space.